The invention relates to a fan drive, particularly one for cooling installations of vehicles.
More particularly, the invention relates to a fan drive which comprises a hydraulic motor, a control valve which regulates the flow of pressure medium through a bypass around the hydraulic motor as a function of the temperature, a control valve, a control spring which biases the control piston in the direction of closing the bypass, a control pressure in the control chamber which also acts on the control piston in the direction of closing the bypass, and a pilot valve which regulates the control pressure and which is actuated by an electromechanical servo element.
A fan drive of this general type is disclosed in German application No. P 32 22 851. A sensitive control of the fan drive is obtained with the installation described in the aforecited application. A very simple configuration of the fan drive is ensured, in particular, by integration of parts and a small number of hydraulic connecting lines. Furthermore, this variable fan drive is universally applicable to different arrangements of hydrostatically driven fan wheels.